U.S. patent number 5,769,333 [Application Number 08/806,526] was granted by the patent office on 1998-06-23 for method of and apparatus for recovering foaming gas of the foamed material.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Masakatsu Hayashi, Nobuo Kimura, Kazuo Makino, Chikao Oda, Kazuo Sakaguchi, Yoshiyuki Takamura, Noritaka Terayama, Kichiji Uchiyama.
United States Patent |
5,769,333 |
Kimura , et al. |
June 23, 1998 |
Method of and apparatus for recovering foaming gas of the foamed
material
Abstract
A system including a method and an apparatus is disclosed for
effectively separating a foamed heat-insulating material, such as
insulated wall sections from used refrigeration equipment, into a
foaming gas and a heat-insulating resin without any alteration and
recovering them. A peeling portion for peeling a foamed
heat-insulating material from a composite material containing the
foamed heat-insulating material is included in a crusher provided
with a high speed rotor having a plurality of hammers and a casing
surrounding the rotor. A sorting portion is provided for sorting
the foamed heat-insulating material with a tilting type wind force
sorter having a limited tilting angle and a limited height of a
wind tunnel. A pulverizing portion is provided for pulverizing the
sorted foamed heat-insulating material and for separating a foaming
gas therefrom. A condensing portion is provided for cooling and
liquefying the separated foaming gas. A compressor is provided for
compressing the pulverized non-foaming gas portions of the
heat-insulating material for reducing the volume thereof. These
recovery steps are accomplished without permitting escape of the
foaming gas to the outside of the system.
Inventors: |
Kimura; Nobuo (Kudamatsu,
JP), Hayashi; Masakatsu (Ushiku, JP), Oda;
Chikao (Kudamatsu, JP), Sakaguchi; Kazuo
(Kudamatsu, JP), Takamura; Yoshiyuki (Kudamatsu,
JP), Uchiyama; Kichiji (Kudamatsu, JP),
Makino; Kazuo (Kudamatsu, JP), Terayama; Noritaka
(Kudamatsu, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
27576637 |
Appl.
No.: |
08/806,526 |
Filed: |
February 24, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
250777 |
May 27, 1994 |
5641128 |
|
|
|
85092 |
Jul 2, 1993 |
5431347 |
Jul 11, 1995 |
|
|
56937 |
May 5, 1993 |
5301881 |
|
|
|
984492 |
Dec 2, 1992 |
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Foreign Application Priority Data
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|
|
|
|
Dec 2, 1991 [JP] |
|
|
3-317643 |
Jan 29, 1993 [JP] |
|
|
5-13385 |
May 27, 1993 [JP] |
|
|
5-125670 |
Dec 28, 1993 [JP] |
|
|
5-334960 |
Feb 24, 1994 [JP] |
|
|
6-26461 |
Feb 24, 1994 [JP] |
|
|
6-26464 |
|
Current U.S.
Class: |
241/24.18;
241/79; 241/101.2 |
Current CPC
Class: |
B02C
13/282 (20130101); B02C 18/142 (20130101); B07B
4/02 (20130101); B02C 21/00 (20130101); B09B
2101/02 (20220101); B02C 19/0056 (20130101); B03B
5/36 (20130101); B29B 17/02 (20130101); B03B
5/28 (20130101); B09B 3/00 (20130101); C08J
11/06 (20130101); B03B 9/061 (20130101); B02C
2018/147 (20130101); B29K 2705/12 (20130101); B29B
2017/0234 (20130101); Y02W 30/52 (20150501); B29L
2031/7622 (20130101); Y10S 241/38 (20130101); B29K
2705/00 (20130101); Y02W 30/62 (20150501); B29K
2075/00 (20130101); B29K 2105/04 (20130101) |
Current International
Class: |
B03B
9/06 (20060101); B03B 9/00 (20060101); B03B
5/28 (20060101); B03B 5/36 (20060101); B07B
4/00 (20060101); B07B 4/02 (20060101); B09B
3/00 (20060101); B29B 17/02 (20060101); B02C
18/06 (20060101); B02C 18/14 (20060101); B02C
009/12 () |
Field of
Search: |
;241/24.18,25,33,101.2,63,79,DIG.38 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Rosenbaum; Mack
Attorney, Agent or Firm: Evenson McKeown Edwards &
Lenahan, PLLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of application Ser. No.
08/250,777 filed May 27, 1994, now U.S. Pat. No. 5,641,128, which
is a Continuation-in-Part application of U.S. patent application
Ser. No. 08/085,092 filed on Jul. 2, 1993, now U.S. Pat. No.
5,431,347 issued Jul. 11, 1995; which is a Continuation-in-Part
application of application Ser. No. 08/056,937 filed on May 5,
1993, now U.S. Pat. No. 5,301,881; which is a Continuation
Application of U.S. patent application Ser. No. 07/984,492 filed on
Dec. 2, 1992, now abandoned.
Claims
What is claimed is:
1. Apparatus for recovering foaming gas from fragments containing
foamed material attached to other solid materials, comprising the
following sequentially arranged devices:
a first crusher with relatively movable parts receiving the
fragments, said first crusher generating a foaming gas from the
foamed material and a mixture of crushed foam material and crushed
other material,
a gas absorbing device connected to said first crusher, said gas
absorbing device absorbing the foaming gas,
a separator receiving said mixture, said separator outputting
separate supplies of crushed foam material and crushed other
materials; and
a recovery device with a foaming gas cooler receiving the crushed
foam materials, said recovery device outputting a liquefied foaming
agent from a recovered foaming gas.
2. An apparatus according to claim 1, wherein said recovery device
is configured to further output a fine powder of compressed foamed
heat-insulating material pieces.
3. Apparatus for recovering foaming gas from fragments containing
foamed material attached to other solid materials, comprising the
following sequentially arranged devices:
a crushing device with relatively movable parts receiving the
fragments, said crushing device generating a foaming gas from the
foamed material and a mixture of crushed foam material and crushed
other material;
a gas absorbing device connected to said crushing device, said gas
absorbing device absorbing the foaming gas from said crushing
device;
a separator receiving said mixture, said separator outputting
separate supplies of crushed foam material and crushed other
materials; and
a recovery device with a foaming gas cooler receiving the crushed
foam material, said recovery device outputting a liquefied foaming
agent from a recovered foaming gas.
4. An apparatus according to claim 3, wherein said recovery device
further outputs compressed foamed heat-insulating material
pieces.
5. An apparatus according to claim 3, wherein said recovery device
includes a pulverizer section for separating the crushed foam
material into a resin component and a foaming gas.
6. An apparatus according to claim 5, wherein said recovery device
includes further recirculating means for recirculating a portion of
a foaming gas back into the pulverizer section to thereby increase
the concentration of foaming gas.
7. Method for recovering foaming gas from fragments containing
foamed material attached to other solid materials, comprising the
following sequential steps:
crushing the fragments with relatively movable parts to generate a
foaming gas from the foamed material and a mixture of crushed foam
material and crushed other material;
absorbing the foaming gas generated by said crushing;
separating said mixture to output separate supplies of crushed foam
material and crushed other material;
recovering the foaming gas from the supply of crushed foamed
material; and
liquefying the recovered foaming gas into a liquefied foaming
agent.
8. A method according to claim 7, wherein said recovering step
further outputs compressed foamed heat-insulating material
pieces.
9. A method according to claim 7, wherein said recovery step
includes a separating step for separating the crushed foam material
into a resin component and a foaming gas.
10. A method according to claim 9, wherein said recovery step
includes a recirculating step for recirculating a portion of a
foaming gas back into a pulverizer section to thereby increase the
concentration of foaming gas.
11. A method according to claim 7, wherein said recovery step
includes a recirculating step for recirculating a portion of a
foaming gas back into a pulverizer section to thereby increase the
concentration of foaming gas.
Description
FIELD OF THE INVENTION
The present invention relates to a method of and an apparatus for
disposing of unnecessary foamed material used in a refrigerator or
the like, and particularly to a method of and an apparatus for
recovering a foaming agent from the above-mentioned foamed
heat-insulating material by degassing of the foaming agent.
BACKGROUND AND SUMMARY OF THE INVENTION
Conventionally, foamed heat-insulating materials to be discarded
have been roughly crushed, and buried under the ground or thrown
into fire together with other refuse material. In recent years, for
environmental protection and resource recovery purposes,
investigations have been made into the possibilities for recovering
the foaming agents from such foamed material.
It is disclosed in German Patent Document DE 4,016,512 A1, for
example, to recovery foaming agents from hard polyurethane foams.
In this method, a hard polyurethane foam material is roughly
crushed by a crusher and compressed by a cylinder press or the
like. A foaming gas is thus discharged from the heat-insulating
material, and is absorbed and degassed by an active carbon or the
like, to be thus recovered.
However, as a result of experiments made by the present inventors,
a hard polyurethane foam heat-insulating material in a volume of 50
mm cubic could not be degassed even by applying of a load of about
5 metric ton (pressure of about 5 metric ton per 25 cm.sup.2). The
degassing was thus judged to be practically difficult by a simple
compression. The reason for this is that the strength of hard
polyurethane foams has been extremely increased in recent years by
the enhancement in the quality of resin and the improvement in the
manufacturing techniques. Accordingly, it is difficult to degas at
the same level by only the compression, both refuse matters
generated several decades ago and those generated using the
recently adopted manufacturing processes.
The present invention covers the whole recovery system, and is made
to solve problems throughout all processes including a
pre-treatment process of taking off a foamed heat-insulating
material from a refrigerator, a process of degassing a foaming gas,
and a post-treatment process for the degassed foamed
heat-insulating material. In the pre-treatment process, it is
intended to effectively and substantially perfectly peel a foamed
heat-insulating material adhered to steel plates and/or plastic
material plates constituting a refrigerator using an apparatus
improved in labor saving, and to then sort only the peeled foamed
heat-insulating material. In the degassing process, it is intended
to perfectly degas the foaming gas. Moreover, in the post-treatment
process, it is intended to reduce the volume of the fine powder of
the resin constituting the foamed heat-insulating material for
facilitating subsequent transportation or the like.
The degassing process is more fully described as follows. To degas
a foaming gas from a foamed heat-insulating material formed of
independent foams, the foam film must be destroyed. The destruction
of the foam film by compression requires a high load, as described
above. For weakening the destruction strength of the foam film, it
is considered to heat the resin of the heat insulating material,
however, the heat-insulating material itself has a heat-insulating
effect essentially and is difficult to be uniformly heated, which
causes the fear that the foaming gas is thermally decomposed. On
the other hand, it may be considered to cool the foamed
heat-insulating material at low temperatures for avoiding the
thermal decomposition for making brittle the heat-insulating
material; however, the heat-insulating material has a function as a
cold insulator essentially, and is difficult to be uniformly
cooled.
It is an object of the present invention to provide a method of and
apparatus for recovering a foaming gas capable of enhancing a
recovery ratio of a foaming gas.
It is another object to provide a system including a method of and
apparatus for recovering foaming gas with labor-saving throughout
the whole system.
According to the present invention, there is provided a crusher
supplied with a fragment having foamed material stuck on another
material. The crusher peels the foamed material from the other
material (e.g., steel plates or plastic plates) of said fragment
and forms a mixture of crushed materials containing crushed foamed
material and crushed other material. A separator is supplied with
said mixture for separating said crushed foamed material from the
other crushed material. A recovering device supplied with said
crushed foamed material from said separator recovers a foaming
agent from said crushed foamed material.
Preferred embodiments of the crusher include a high speed rotor
having a plurality of hammers, and a casing having an irregular
inner wall surface wherein the foamed heat-insulating material is
impact-crushed and grounded.
Preferred embodiments of the separator include a tilting type wind
force sorting unit with wind force conveying of the foamed material
to an upper conveyor outlet opening while the other solid materials
are conveyed downwardly by gravity along a tilting bottom surface
of the conveyor unit to a lower conveyor outlet opening. The bottom
tilted surface of the wind tunnel section of the sorting unit is
inclined at an angle greater than an angle of repose based on the
coefficients of friction of the bottom tilted surface and the metal
or plastic plates forming the solid material of the mixture. Thus,
the plastic or metal slides downwardly under the force of gravity
against the upwardly flowing wind force which conveys the foamed
material upwardly thereby separating the foamed material from the
metal and/or plastic plates.
The recovering device preferably includes a pulverizing device for
exerting an external force to the foamed heat-insulating material
for destroying independent foams in the foamed heat-insulating
material, thereby separating the foamed heat-insulating material
into a resin component and a foaming gas within the foam. The
recovering device also includes a condensing device for cooling and
liquefying the separated foaming gas. A compressor is provided
which includes a cylinder having an opening portion on a side
surface, a main drive piston with a straight barrel portion having
a length longer than that of the opening portion in the axial
direction of the cylinder, and a driven piston with a straight
barrel portion having a length shorter than that of the main drive
piston, the main drive piston and the drive piston being disposed
on both the sides of the cylinder while holding the opening portion
therebetween, wherein a fine powder of the resin component of the
foamed heat-insulating material charged from the opening portion is
compressed by movement of the main drive piston on the drive piston
side, and at the same time the opening portion of the cylinder is
closed by the straight barrel portion of the moved main drive
piston, and the compressed fine powder is discharged from the end
surface of the cylinder on the driven piston side by movement of
the main drive piston and the drive piston on the driven piston
side.
A foamed heat-insulating material adhered to plastic or metal
material is put in the crusher, and is impact-crushed and ground
between a crusher rotor and a crusher casing, thereby peeling the
foamed material from the plastic or metal. The mixture of the
peeled foamed heat-insulating material and the plastic or metal is
then supplied to the tilting type wind force sorter. In this
sorter, the planar plastic or metal is slid along the bottom plate
of the wind tunnel. The planar plastic or metal pieces are
orientated substantially flat and parallel to the wind direction,
as a result of which the resistance of the plastic or metal against
the wind is significantly reduced. Thus, in terms of the ease of
the flying against the wind, a large difference is generated
between the plastic or metal and the foamed heat-insulating
material. This makes it possible to sort out only the foamed
heat-insulating material with a high accuracy. The sorted foamed
heat-insulating material is then applied with an external force to
destroy individual foams in the foamed heat-insulating material.
Accordingly, it is possible to substantially perfectly degas the
foaming gas. On the other hand, the fine powder of the pulverized
foamed heat-insulating material is charged in the cylinder under
the pulverizing portion by the deadweight, and is then compressed
and discharged while discharging the foaming gas remaining in the
fine powder on the pulverizing portion side.
Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration showing the construction of one
embodiment of a recovery system, constructed according to a
preferred embodiment of the present invention;
FIG. 2 is an enlarged schematic front view showing details of a
wind force sorter shown in FIG. 1;
FIG. 3 is a schematic view showing the structure of a conventional
wind force sorter;
FIG. 4 is a graph comparing the performance of a wind force sorter
of the present invention such as shown in FIG. 2 with that of a
conventional wind force sorter such as shown in FIG. 3;
FIG. 5 is a graph explaining the influence of the wind speed and
wind tunnel height on the sorting efficiency of a wind force sorter
of the present invention;
FIG. 6 is an enlarged sectional schematic view showing an important
portion of a pulverizing portion of the recovery system of FIG.
1;
FIG. 7 is a graph showing a particle size and a degassing ratio for
foamed heat-insulating material pieces after being pulverized by a
pulverizer of the present invention;
FIGS. 8 to 11 are sectional views of a cylinder, piston and the
like for explaining the action of a compressor of the present
invention;
FIG. 12 is an enlarged detailed sectional view of FIG. 11;
FIG. 13 is an enlarged sectional view of FIG. 11 for explaining the
operation of the compressor of FIGS. 8-12; and
FIG. 14 is a schematic illustration showing the structure of a
recovery system constructed according to another embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, one embodiment of the present invention will be
described with reference to FIGS. 1 to 12.
FIG. 1 is a diagram showing the basic concept of a recovery system
constructed according to a preferred embodiment of the invention. A
refrigerator 1 or the like containing foamed heat-insulating
material adhered to solid plastic and/or metal plates is roughly
crushed by first crusher 2. The roughly crushed parts are then put
in a crusher 3. The crusher 3 includes a rotor 5 rotatable at a
high speed and having a plurality of hammers 4, and a casing 6
having an irregular inner wall surface surrounding the rotor 5. A
majority of the foamed heat-insulating material before being put in
the crusher 3 is stuck or adhered on a plastic material plate,
metal plate or the like. This material is held between the rotor 5
and the casing 3 in the crusher 3 while it is impact-crushed and
ground, and is peeled from the plastic material and the like. Of
the peeled crushed pieces, those having small sizes pass through a
grid 8 at a discharge port 7, and are put in an inlet 10 of a wind
force sorter 9 in the subsequent process; however, those having
large sizes which cannot pass through the grid 8 remain in the
crusher 3, and are furthermore peeled from the plastic material or
the like. As a result of experiments by the present inventors, 98%
or more of the foamed heat-insulating material stuck on the plastic
material or the like can be peeled off in such a crusher 3.
Next, the wind force sorter will be fully described with reference
to FIG. 2.
The wind force sorter 9 has a structure in which a wind from a
blower 11 flows toward a screen 12 by way of a wind tunnel. The
mixture is fed to the wind force sorter by inlet 10 and a rotary
valve 19 which assures a consistent constant flow of material. A
tilting angle 8 of the wind tunnel portion is larger than an angle
of repose based on a wall surface friction coefficient of a bottom
plate 13 of the wind tunnel portion and a solid part friction
coefficient of plastic pieces 14, metal pieces 15 or the like, so
as to permit the plastic or metal pieces to slide along the tilting
surface under the force of gravity without staying even against a
wind flowing upward in the wind tunnel. The plastic pieces or the
like are thus slid downward along the tilting surface, and
recovered in a plastic/metal recovery box 16. On the other hand,
the foamed heat-insulating material pieces 17 moved on the leeward
side are fed to the subsequent pulverizing portion. Of the crushed
pieces put in the wind force sorter, the majority of the plastic
pieces or the like peeled from the foamed heat-insulating material
pieces are of planar shapes, and the planar plastic pieces or the
like are slid with the planes thereof being directed to be in
parallel to the bottom plate 13 of the wind tunnel, so that each of
the plastic pieces or the like has a small resistance against the
wind flowing upward in the wind tunnel. Thus, in terms of the ease
of flying against the wind, a large difference is generated between
the bulky foamed heat-insulating material pieces and the plastic
pieces. This will be described in comparison with a conventional
machine.
In the conventional wind sorter, for example, shown in FIG. 3, in
the case that the planes of planar plastic pieces or the like are
disposed parallel to the wind direction, the planar plastic pieces
or the like are difficult to be conveyed by the air current
compared with foamed heat-insulating material pieces having a
specific gravity smaller than that of the plastic or the like, so
that they can be easily sorted from the foamed heat-insulating
material pieces. However, in the case that the planes of the planar
plastic pieces or the like become perpendicular to the wind
direction, the plastic pieces or the like are easily conveyed
similarly to the foamed heat-insulating material pieces, and thus
the sorting accuracy is substantially impaired.
In contrast to the wind force sorter of FIG. 3, in the wind force
sorter of the present invention, as shown in FIG. 2, the planes of
the plastic pieces or the like are substantially always in parallel
to the wind direction due to their accumulation and sliding on the
wind tunnel bottom plate with resultant high sorting accuracy.
FIG. 4 graphically shows the results of experiments which were
conducted by the present inventors, for a mixture of crushed pieces
of planar plastic and bulky foamed heat-insulating material. This
graph shows the recovery ratio, and the mixing ratio of the plastic
pieces in the recovered foamed heat-insulating material pieces. In
this figure, the black dot and the white dot indicate the recovery
ratios of the inventive sorter and the conventional sorter,
respectively. Furthermore, the black triangular dot and the white
triangular dot indicate the mixing ratios of the inventive sorter
and the conventional sorter, respectively. In the wind force sorter
of the present invention, the ideal sorting with 100% of the
recovery ratio and 0% of the mixing ratio can be achieved at the
wind speed (4.8 m/s) shown by the solid line arrow <a>. On
the contrary, in the conventional sorter, only the sorting with
about 80% of recovery ratio can be achieved at a wind speed (5.1
m/s) shown by the broken line arrow <b>. Furthermore, in the
conventional sorter, when the wind speed is increased up to the
value shown by the arrow <c> (5.8 m/s) for increasing the
recovery ratio, 95% of the recovery ratio can be obtained but the
mixing ratio is increased up to about 40%. As a result, in the
conventional sorter, a wind speed for satisfying both the recovery
ratio and the mixing ratio cannot be found.
The height <h> of the wind tunnel of the sorter (FIG. 2) will
be described below.
Along with the increase in the supply amount of the mixture within
this sorter, a lot of the plastic pieces tend to be slid along the
wind tunnel floor surface, leading to a reduction in the wind speed
near the floor surface. As a result, the foamed heat-insulating
material pieces flying upward near the floor surface are grounded
on the floor surface. The wind speed near the floor surface is thus
furthermore reduced. Eventually, the foamed heat-insulating
material pieces are slid downward along the floor surface, to be
recovered into the plastic recovering portion, thereby reducing the
recovery ratio of the foamed heat-insulating material. In this
case, since the amount of the wind in the wind tunnel is set to be
constant, the reduction in the wind speed near the floor surface
increases the wind speed at the central portion of the wind tunnel
which is higher than the floor surface. When the height of the wind
tunnel is excessively increased with respect to the size of the
foamed heat-insulating material pieces, the foamed heat-insulating
material pieces are slid downward along the floor surface by the
reduced wind speed near the floor surface. However, when the height
of the wind tunnel is set to be lower, the foamed heat-insulating
material pieces which are intended to be slid downward are moved
upward by the wind at the center portion separated from the floor
surface of the wind tunnel. This makes it possible to prevent the
reduction in the recovery ratio of the foamed heat-insulating
material pieces even when the supply amount of the mixture is
increased.
FIG. 5 shows the recovery ratio affected by the wind speed for the
constant processed amount. The wind speed shown by the abscissa is
measured at the central portion of the wind tunnel in the height
direction (h of FIG. 2) before specimens such as foamed
heat-insulating material pieces are put in the wind tunnel. This
FIG. 5 shows the recovery ratio versus wind speed for three
different wind tunnel height conditions as a function of the
maximum size "d" of the foamed neat-insulating material pieces. In
this figure, at the wind speed of 4.9 m/s, when the height of the
wind tunnel is twice as much as the maximum size of the foamed
heat-insulating material pieces, the recovery ratio is 96%; when it
is 2.5 times, the recovery ratio is about 90%; and when it is 5
times, the recovery ratio is reduced to 55%. The result shows that
the height of the tunnel is preferably set to be 2.5 times or less
as much as the maximum size of the foamed heat-insulating material
pieces. Since the maximum size of the foamed heat-insulating
material pieces is about 60 mm, the height of the wind tunnel is
preferably specified to be 150 mm or less.
The foamed heat-insulating material pieces sorted in the wind force
sorter described above pass through both a longitudinal hopper 18,
having two rotary valves 19, and a screw feeder 20, as shown in
FIG. 1, and are supplied to a pulverizer 21 in the subsequent
process. The pulverizer is intended to degas the foaming gas, and
it supplies a mixed gas of the degassed foaming gas and air put in
the pulverizer together with the foamed heat-insulating material
pieces, to a condenser 27. In this case, when the concentration of
the foaming gas is high, a high condensing efficiency can be
obtained. The above-noted rotary valves 19 prevent the degassed
foaming gas from flowing backward and being leaked from the screen
12 or the like to the outside of the system. FIG. 6 shows an
important portion of the pulverizer 21. The pulverizer 21 includes
sawtooth fixed blades 22 and planar rotary blades 23. Each of the
foamed heat-insulating material pieces 17 are pushed into a gap
(about 1 to 2 mm) between the leading edge of a rotary blade 23 and
a fixed blade 22, to be thus pulverized by the shearing force. In
the case that the foamed heat-insulating material is a hard
polyurethane foam, the velocity gradient corresponding to the
shearing force acted at material piece 17, as defined by a division
of the gap length divided by a circumferential velocity of the
leading edge or rotary blade 23, is required to be in the range of
1000/s (s=second) or more, preferably, in the range of 5000/s to
50000/s. In the example shown in FIG. 6, the necessary shearing
force can be obtained by setting the rotational speed of the rotary
blade at about 3000 rpm.
The pulverizer is not limited to the rotary type, and may be of a
type capable of exerting a dynamic force to the heat-insulating
material pieces. For example, there may be used an impact
pulverizer including a pair of rotors having rotary blades around
respective outer peripheries for exerting an impact force to the
heat-insulating material pieces between the rotary blades.
FIG. 7 shows one relationship between the particle size of foamed
heat-insulating material pieces after being pulverized using a
pulverizer and a degassed foaming agent by the present inventors.
As is apparent from this figure, when the foamed heat-insulating
material pieces are pulverized up to the particle size of about 0.4
mm, that is, to the degree of the diameter of the independent foams
in the foamed heat-insulating material pieces, the foaming agent is
substantially perfectly degassed.
In addition, at a tank 24 and the screw feeder portion shown in
FIG. 1, there is generated a pressure variable wave due to the
impact caused by pulverization. The pressure variable wave is
propagated to the hopper 18 described above, which causes the
danger that the degassed foaming gas flows backward and is leaked
to the outside of the system through the screen 12 of the wind
force sorter. However, this flow-out of the degassed foaming gas is
prevented because the foamed heat-insulating material pieces in the
longitudinal hopper 18 serve as damping material, the rotary valves
19 extremely reduce the amplitude of the pressure variable wave,
and the gas is absorbed by a compressor 26 described later.
The foaming gas generated in the pulverizer 21 passes is through a
bag filter 25 and is compressed by the compressor 26. This foaming
gas is liquified by a condenser 27 and is then recovered in a
collecting tank 28.
Next, a compressor 30 for compressing a fine powder 29 of resin
material of the foamed heat-insulating material pieces pulverized
in the pulverizer will be described with reference to FIGS. 8 to
12. In FIG. 8, numeral 31 indicates a hopper 31, 32 is a cylinder,
33 is a main drive piston with a straight cylinder portion longer
in length than an opening portion A of the cylinder, 34 is a driven
piston for receiving a reaction force when the main drive piston
compresses the fine powder of the foamed heat-insulating material
pieces. The fine powder of the foamed heat-insulating material
pieces are charged by their deadweight into the cylinder 32 by way
of the hopper 31. At this time, the driven piston 34 is contacted
with the end surface of the cylinder at the point B. The drive
piston 33 is moved leftward to compress the fine powder while
discharging the foaming gas present in gaps within the fine powder
upward on the hopper side as shown by the arrows until the leading
edge of the drive piston 33 passes through the opening portion
(broken line C). After that, as shown in FIG. 9, since the diameter
of the leading edge of the drive piston 33 is slightly reduced, the
foaming gas is discharged into the hopper 31 as shown by the
arrows. Thus, as shown in FIG. 10, when the drive piston 33 is
sealed by a sealing material 35 such as an o-ring, the compression
is completed. Next, as shown in FIG. 11, the drive piston 33 and
the driven piston 34 are simultaneously moved rightward, to
discharge the fine powder of the compressed foamed heat-insulating
material pieces from the discharge port 37 to the outside of the
system.
FIG. 12 shows further details of the compressor. The leakage of the
foaming gas can be prevented by the sealing material 35, a packing
38 and a dust sealing material 39.
Moreover, when the compressed foamed heat-insulating material is
discharged, it can be easily separated from the piston by bonding a
sticking preventive material 40 such as fluoride resin or the like
on the end surface of the piston.
In certain preferred embodiments, foaming gas which is not
liquified in the condenser is recirculated into pulverizer 21 as
schematically shown by dotted line 27A in FIG.1. This recirculated
gas can assist in cooling the pulverizer and in increasing the
recovery ratio of the foaming gas.
The following is a description of a second embodiment of a
compressor 30A as shown in the sectional view of FIG. 13. Other
than as noted below with respect to the air nozzles 39A and valves
40A, this compressor is similar to the compressor 30 of the
embodiment of FIGS. 1-12. When the fine powder of the foamed
heat-insulating material is compressed by the compressor shown in
FIG. 1, a mixed gas of a foaming gas and air in a slight amount is
present in gaps within the fine powder, which is discharged to the
outside of the system as it is. The formation of the gaps is
dependent on the compressed load of the piston. Accordingly, as the
concentration of the foaming gas is lowered for the same compressed
load, the foaming gas discharged to the outside of the system can
be reduced. In the embodiment of FIG. 13, air is blown in the
compressor 30A from the outside, to lower the concentration of the
foaming gas contained in the fine powder of the foamed
heat-insulating material, thereby reducing the discharged foaming
gas. FIG. 13 shows nozzles 39A having valves 40A for blowing air in
the fine powder 29A within the cylinder 32A.
Other than this modified compressor with a supply of air to the
fine powder as shown in FIG. 13, this second embodiment is similar
to the embodiment of FIGS. 1-12.
FIG. 14 shows a third embodiment of the invention. This embodiment
is similar to the FIG. 1 embodiment except the crusher 3 is
provided with a discharge port 41 and an absorbing agent 42. When
being peeled, the foamed heat-insulating material is partially
crushed with consequent release of foaming gas. The foaming gas
thus degassed is absorbed by the absorbing agent 42 through the
discharge port 41. Also, by heating the absorbing agent 42 with a
specified interval, it is possible to furthermore enhance the
recovery ratio of the foaming gas. Since the remainder of this
embodiment of FIG. 14 is similar to the embodiment of FIG. 1,
further details are included with the above description of FIG.
1.
According to the present invention, it is possible to easily and
highly effectively separate a foamed heat-insulating material into
a foaming gas and a heat-insulating resin without any alteration,
and to recover them with high recovery ratios respectively.
Although the invention has been described and illustrated in
detail, it is to be clearly understood that the same is by way of
illustration and example, and is not to be taken by way of
limitation. The spirit and scope of the present invention are to be
limited only by the terms of the appended claims.
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